In today's changing environment, the next threat our nation's warfighter face may not be on a traditional battlefield. Instead, it may be a chemical or biological attack without notice.
A new project funded by the Defense Threat Reduction Agency's Joint Science and Technology Office and conducted by a team of Lawrence Livermore National Laboratory (LLNL) scientists have created a new material that is breathable and protects against biological and chemical threats. This futuristic material or ‘second skin' will offer more protection for our warfighters in contaminated environments by sensing and reacting to chemical and biological threats.
September 29, 2016 - A new project funded by the DTRA's Joint Science and Technology Office and conducted by a team of Lawrence Livermore National Laboratory (LLNL) scientists have created 'second skin,' a new material that is breathable and protects against biological and chemical threats. (Courtesy photo provided by DTRA Chemical and Biological Technologies Department)
ICurrent protective military uniforms have heavyweight full-barrier protection or permeable adsorptive protection that cannot meet the critical demand of simultaneous high comfort and defense. They also pose a high heat burden to warfighters and do not react to environmental threats. High breathability is a critical requirement for protective clothing to prevent heat-stress and exhaustion when military personnel are engaged in the field.
The JSTO/LLNL ‘second skin' offers a ‘smart' material that reacts to the environment by blocking chemical agents from penetrating the warfighter's uniform. “Second skin” blocks harmful agents such as sulfur mustard (blister agent), GD and VX nerve agents, toxins such as staphylococcal enterotoxin and biological spores such as anthrax.
The LLNL team, managed by Tracee Whitfield from DTRA, fabricated flexible polymeric membranes with aligned carbon nanotube (CNT) channels as moisture pores. Each pore is less than five nanometers, 5,000 times smaller than the width of a human hair. The new composite material provides high breathability utilizing unique transport properties of these CNT pores. By quantifying the membrane permeability to water vapor, the team found for the first time that, when a concentration gradient is used as a driving force, CNT nanochannels will sustain gas-transport rates exceeding that of a well-known diffusion theory by more than one order of magnitude.
These membranes also provide protection from biological agents due to their minuscule pore size. Biological threats such as bacteria or viruses are typically larger than 10 nm, much larger than the LLNL-designed composite material. Laboratory tests demonstrated the CNT membranes' ability to repel Dengue virus during filtration tests.
This confirms that LLNL-developed CNT membranes provide effective protection from biological threats by size exclusion rather than by preventing wetting. Furthermore, these results demonstrate that CNT pores combine high breathability and bio-protection in a single functional material.
However, chemical agents are much smaller in size and require the membrane pores react to block the threat. To encode the membrane with a smart and dynamic reaction to small chemical hazards, Massachusetts Institute of Technology (MIT) scientists are modifying these CNT membranes with chemical-threat-responsive functional groups.
These functional groups will sense and block the threat like gatekeepers on the pore entrance. Recently, LLNL and MIT integrated actuating polymers with single walled CNTs to demonstrate a chemiresistive dosimetric material. These materials are the foundation of a low cost, passive, wireless hazard badge that will allow detection of nerve agents.
This spin-off technology effort was funded within the ‘second skin' project as basic research; however, plans are underway to develop a wireless sensor integrated with responsive protective fabrics for the detection of exposure and material response to chemical warfare agents. This is a paradigm shift from the concept of a deployable sensor that is worn as a badge; as LLNL and MIT would embed sensors in the fabric itself. As the fabric reacts to provide protection, the physical-chemical change in the fabric can be measured and analyzed. Swatch evaluations will occur in early 2018 to demonstrate the concept of ‘second skin,' a major milestone that is a key step in the maturation of this technology. The new uniforms could be deployed to the field in less than 10 years.
By Elizabeth Meixler, Defense Threat Reduction Agency
Provided through DVIDS
Comment on this article